In the manufacture of crankshaft bearing caps for automobile engines, up to five bearing caps were cast together as a unit referred to in the trade as a "monoblock". The monoblock process consisted of casting several items of a similar shape as a single piece, and then separating them by sawing or broaching into several individual items. For many years, the monoblock casting method has been used for crankshaft bearing caps.
Prior to 1987, all machining of bearing cap bolt holes was done while the individual bearing caps remained in the monoblock condition (i.e. not separated from one another). In that earlier process, the separation into individual bearing caps was carried out as one of the last machining operations.
In 1987, however, the manufacturing processing of automotive-type crankshaft bearing caps was changed dramatically. Although the casing of the bearing caps as a monoblock did not change, the means of dimensioning the finished individual bearing caps changed considerably. The dimensional changes required the development of new methods to handle the bearing caps between the manufacturing operations.
Essentially, the new dimensioning requirements involved tighter tolerances relative to the side and lock notch faces, and required that bolt hole machining be accomplished after the separation of the monoblock into individual bearing caps. In order to properly fixture the individual bearing caps after division of the monoblock, the caps must be separated or spread apart. The present invention provides an apparatus capable of accurately spreading apart the various bearing caps into which monoblock is divided. Again it is emphasized that although the present apparatus was developed specifically for crankshaft bearing caps, the underlying concept of the design is applicable to any parts with similar shapes.